Hey everyone, thanks for coming back to Wi Fi fundamentals with location and analytics. This course will help you to muster the air we are moving to the five gigahertz band and this one is a best. five gigahertz provides faster data rate at a shorter distance. Remember that the higher frequency the shorter wavelength and attenuation is faster, but it's Wi Fi band The location is way bigger than 2.4. So much more bandwidth can be occupied and the amount of devices using them is rare. Most is embedded devices supports 2.4.
We can see that it's in frequency band. There are so many 20 megahertz channels to choose from. to bond them together for a wider channel, it actually has six times capacity than the 2.4. And so 802 11 n and AC standards both introduce changes in the MAC layer that allows them to add bonded channels 802 11 n introduced high throughput channel, a maximum of 14 megahertz channel 802 11 ac also supports a very high throughput channels up to 160 megahertz channel. bonding is quite an amazing way to gain throughput, but be aware at least at the 802 11 and when it comes to 2.4 gigahertz band 40 megahertz channel will overlap with just about any other channel in your surrounding enable to 11 ac it is not an issue, you can use 40 megahertz channels, you can use 80 megahertz channels although, as you will see, in most cases in dense area, we use 20 to 14 megahertz channels and you can even use up to 160 megahertz channel 802 11 ac also applied a new channel naming their number by their center channel in a 40 megahertz channel that is the result of channel 36 and 40.
The new channel will be called channel 38. And when it comes to To an 80 megahertz channel, that is the result of channel 36 4044 and 48. The new channel will be called channel 42. Is there a good reason to use wide channels? Well, yes, it has much more throughput but be aware 80 megahertz channels makes much more noise in the air then a 40 or a 20 megahertz channel and co channel interference can still exist if you're in an high density area with a lot of 80 or 160 megahertz channels around you're better to plan around the non overlapping 40 megahertz channels and even 20 megahertz channels in an enterprise conditions while I'm in the middle 211 n 20 megahertz channels, my noise level is minus 96. Moving on to the 802 11 ac 80 megahertz wide channels, we can see that my noise level actually increased twice minus 90 tree a tree dBm difference.
When we looked at our frequency table before, we saw that part of it were non DFS bands. What is a DFS? Well, five gigahertz is also the frequency of choice for radars. DFS is a dynamic frequency shift. Whenever access point senses that there is a radar around it. It looks for a new channel and lets every station in its area know about it through the usage of an 802 11 H message it applies to the 50 to 50 up to the 5750 megahertz band.
Another mechanism is TPC, but this one is all about power management, it can work out when there is a radar around or in case our access point is in a very congested area and it wants the stations to lower their power. So which one to choose the 2.4 or the five gigahertz band when there is no straight answers. Most access point nowadays are dual band. Just think of it as two cells in your environment. Each takes its own airtime. Most station nowadays will prefer to connect to the five gigahertz frequency as it allows them more throughput.
We will see many cases there are a piece transmission power for the five gigahertz band is stronger from the 2.4 gigahertz. The reason is the short range of the five gigahertz frequency. Another popular feature of access points is been steering. Our access point detects five gigahertz supporting device and student to that frequency instead of the 2.4 gigahertz which they probably would connect because of its stronger signal. That's all next up frames. See you soon